Though he appeared very collected, a little part of Sora was worried about the things she had said. They did have a rocky bit in their relationship just now, but they had talked about it. He looked confident of course, but it bothered him how poorly Riku's Mother thought of him. He felt offended and almost a little upset at her accusations, but it didn't change his mind about how he cared for Riku.
"Then I wanted to say thank you for letting me stay over this winter break," Sora told her. It bothered him how she hated him, but his Mom taught him manners. "Losing my parents has been really hard, but I appreciate the kindness I've been shown by everyone else." Everyone not including her at this point, pretty much.